22 years old male hit from a car on the roadside of an urban area.The ground EMS ambulance (physician, nurse staffed), dispatched on scene, find the patient alert, oriented and spontaneously breathing. His vitals are:GCS 15 , RR 20, SaO2 95, HR 85, SBP 110No mention of head trauma.Chest no sign of trauma, bilateral and equal expansion and air entry.Pulse is strong.He has a profound laceration with loss of substance but not evisceration on left flank and no external bleeding from the wound.The abdomen is painful and resistant to palpation in left flank.There is an open fracture to left tibia (VNS 9).The ground team, after the primary survey, activates the local medical helicopter.The place is 10 k from a level 1 Trauma Center on a local road in an urban area and the helicopter is at 10 minutes flight distance. There is a safe landing space at 500 mt from the point of the accident.A Level 2 hospital (general surgery, orthopedics, anesthesiologist, radiology and laboratory 24/7) is at 2 km distance from the scene.Is this a proper activation for HEMS?What international litterature says about advantages of air medical service vs ground medical service?

So what about the case?

Severity: The patient is slightly tachycardic, and the mechanism of trauma give us some clue on possible abdominal injuries, so he need a quick transport to an hospital with a general surgery (and orthopedics naturally for the tibial fracture)

Speed: non simultaneous activation. This kind of missions become competitive on long distances (45 miles) from Level 1 Trauma center (or the appropriate hospital). So GEMS is faster anyway.

Trauma center access: no difference between HEMS and GEMS and even there is doubt on the fact that this patient really need a Level 1 Trauma Center

Crew: this patient does not need an over skilled staff for some particular procedure.

We can conclude that for the standard HEMS activation criteria, this is not an appropriate activation and the best way to reach the hospital for this patient is a ground ambulance.Any suggestion on the theme treated is, as usual, very welcome

In the considered articles I found no mention of this confounders. When they talk about hospital discharge there is mo mention if the discharge was decided from the physicians or from the patient. In the HEMS missions table there was no discrimination based on time of the day,